1. Field of the Invention
The present invention is generally related to a cooling system for a marine propulsion device and, more particularly, to a cooling system for a stern drive propulsion device which provides a cover under which water can be sprayed to provide additional cooling to certain portions of the out drive component of the stern drive system.
2. Description of the Prior Art
U.S. Pat. No. 1,099,684, which issued to Barlow et al on Jun. 9, 1914, describes an engine cooling system which draws water from a body of water in which a marine vessel is operated and directs the water to a cooling Jacket of an internal combustion engine of a marine propulsion device.
U.S. Pat. No. 3,240,181, which issued to Chandler et al on Mar. 15, 1966, describes an outboard motor attachment that comprises a scoop disposed behind a propeller of a marine propulsion device. The system is intended for use when a normally operable cooling system fails.
U.S. Pat. No. 4,075,969, which issued to Griffin on Feb. 28 1978, describes an auxiliary water system for an outboard motor. A cooling water system is adapted to be used with an outboard motor when its water pump has failed. It includes a conduit adapted to have one end connected to one of the two water outlets adjacent the portion of the motor above the shaft housing of an outboard motor. An enlarged inlet is secured to the other end of the conduit and is releasably connected to the lower portion of the shaft housing so that it faces forward to receive water flow responsive to movement of the motor through the water.
U.S. Pat. No. 4,371,351, which issued to Tousey on Feb. 1, 1983, describes a marine stern drive cooler. The cooling apparatus is intended for use with a stern drive unit which has a conduit for carrying water from below the water level to a position over the marine stern drive unit so that water can be sprayed on the stern drive unit. A water receiving aperture is in communication with a lower unit of the conduit and opens generally horizontally and forwardly for receiving water into the conduit. A water dispensing aperture communicates with an upper portion of the conduit and dispenses the water on the exterior of the marine stern drive unit thereby cooling a portion of the unit out of the water.
U.S. Pat. No. 4,595,372, which issued to Hebert on Jun. 17, 1986, describes a water ejector and injector attachment for boats. A water ejector and injector attachment for the motor of a boat comprises a motor adapted to be secured to the frame of the boat carrying a propeller at its lower end and defining a cavitation plate extending rearwardly thereof and having a bore therethrough, at least one recess in the lower surface of the cavitation plate and a trim tab projecting downwardly from the cavitation plate and positioned adjacent rearwardly of the propeller. The trim tab has a passageway therethrough having one end communicating with the bore of the cavitation plate. A plate member integral therewith and has at least one protrusion upwardly extending therefrom, each of the protrusions mates in the recession of the cavitation plate. An elongated tube is provided through the bore in the cavitation plate with one end secured to and communicating with the passageway of the trim tab and the other end terminating in the bilge of the boat. A spring biases the trim tab upwardly whereby the protrusions engage the recesses in the cavitation plate. A handle is provided for moving the trim tab downwardly to disengage the protrusions from the recesses thereby allowing rotational movement of the trim tab.
U.S. Pat. No. 5,340,345, which issued to Brodbeck et al Aug. 23, 1994, describes a water pickup and cooling apparatus for boat drive system. It comprises a water pickup for gathering water from the body of water in which the boat is operating and a spray nozzle that directs a stream of cooling water towards the outer surface of the housing containing the drive assembly gears and shafts. The drive assembly of a typical stern drive for a boat is the linkage that transmits the power generated by the engine to the propeller. To remove the excess frictional heat generated within the drive assembly under high horsepower operation, a cooling apparatus collects water through a water intake opening when the boat is moving forward through the water. A lip formed adjacent to the intake opening assists in directing the water into the opening and forces the water up to and through the spray nozzle. The cooling water is discharged through an opening in the spray nozzle and is directed towards the rear surface of the drive assembly housing. Additionally, a spray direction plate may be mounted on the drive assembly housing to assist in the distribution of the cooling water over the outer surface of the drive assembly housing.
U.S. Pat. No. 5,871,380, which issued to Claussen on Feb. 16, 1999, describes an intercooler for a stern drive of a boat. The intercooler for the stern drive of a boat includes a cover that is attached to the stern drive housing. The cover includes an inner compartment which communicates internally with the stern drive and accommodates lubricating oil used by the stern drive. An outer jacket is disposed adjacent the compartment. Ambient water is introduced into and discharged from the water jacket such that the ambient water circulates through the jacket to cool the inner compartment and the oil contained therein.
U.S. Pat. No. 6,241,566, which issued to Kermis et al on Jun. 5, 2001, describes a cooler for a marine stern drive. A cooling apparatus for the stern drive unit of a marine inboard-outboard drive system is described. It uses the ram effect and has an intake tube carried on the stern drive unit with its intake end in the water. The tube has an intake port held below the water surface for accepting water by the ram effect while the boat is moving forward. The water is carried by the tube to a system for delivering water from the intake tube to the stern drive unit for cooling it. According to the invention, the bottom of the intake tube is closed and the intake port is formed closely adjacent to the bottom of the tube in a selected part of a wall facing forward when the boat is in a forward motion.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Products called xe2x80x9cdrive showersxe2x80x9d are available commercially for attachment to stern drive devices. These products comprise a tube that is shaped to be attached to an fit the contours of a stern drive device, with inlet ends disposed below a surface of water when the stern drive is operated on a body of water. The water is caused to flow through the conduit, as a result of a ram action, and flows upwardly through the conduit to a series of openings within the conduit that are disposed above a heat producing portion of the out drive of the marine propulsion device. Devices of this type are available in commercial quantities from the Simrek Corporation and are referred to as xe2x80x9cMultiport Drive Showers.xe2x80x9d
Those skilled in the art of marine propulsion devices are knowledgeable of many different, systems that are used to cool the out drive of a stern drive system. These systems include internal passageways that direct water through the heat producing portions of the system and typically flow through water jackets formed in castings of the out drive housing and through water jacket passages within the engine itself. In addition, many types of water cooling systems are known which draw water from a body of water in which the marine propulsion device is operated and cause that water to be directed against various outer surfaces of the housing to cool those surfaces and, in turn, to remove heat from heat producing components within the out drive itself. These heat producing components include, but are not limited to, bevel gears that transmit torque between a horizontal shaft driven by an engine and a vertical driveshaft which is contained within the out drive housing.
Known systems that provide showers over the outer surfaces of the out drive housing exhibit a common inherent deficiency. When a marine vessel is operated at high speed, the turbulence behind the transom of the marine vessel and the speed to of the vessel itself cause a significant portion of the cooling water to be caught in the turbulence and forced away from the surface that is intended to be cooled. Although some of the water from the drive showers contacts the outer surface of the heat producing region of the housing, a significant portion of the water can be blown away from the surface by the significant turbulence that exists around the out drive housing when the marine vessel is being operated at high speed. Even the water that moves into contact with the housing is often blown away from the surface by this turbulence and its opportunity to remove heat from the housing is diminished.
It would therefore be significantly beneficial if a cooling system could be provided which forces cooling water to remain in contact and in efficient thermal communication with the outer surface of the out drive housing for an extended period of time even when significant turbulence exists around the out drive.
A cooling system for a marine propulsion device, made in accordance with the preferred embodiment of the present invention, comprises a conduit having an inlet end and an outlet end. The inlet end is disposed below a surface of a body of water when the marine propulsion device is operated normally on the body of water. The outlet end is disposed proximate a heat producing portion of the marine propulsion device. A cover is removably attached to the marine propulsion device to define a space between the cover and the marine propulsion device. The outlet end of the conduit is configured to direct a stream of water into the space.
In a preferred embodiment of the present invention, the inlet end is disposed below an anti-cavitation plate of the marine propulsion device and the conduit, in one embodiment, extends at least partially through a portion of the marine propulsion device. In a typical application of the present invention, the marine propulsion device is an out drive of a stern drive system and the heat producing is portion comprises bevel gears within the propulsion device. The outlet end of the conduit is disposed above a housing portion of the marine propulsion device in which the bevel gears are disposed. The inlet end of the conduit can be formed as a portion of a trim setting device, such as a trim tab. The inlet end can comprise a water scoop disposed below the anti-cavitation plate of the propulsion device.
The cover is shaped to define a return passage between the cover and the marine propulsion device. The return passage is shaped to permit water to flow from the space back to the body of water. The cover is attached to the marine propulsion device at a location above a top portion of a vertical drive shaft. The axis of rotation of the vertical drive shaft intersects the cover in a preferred embodiment. The inlet end is disposed above a propeller of the marine propulsion device. A stream of water is directed from the outlet end in a forward direction onto a top surface of the marine propulsion device in a particularly preferred embodiment.